What I'm saying is that dating methods that may possibly work for up to 2,000-3,000 years ago may not necessarily work for going back further than that. It assumes you can extrapolate. It does not allow for other factors that may have intervened and skewed the data.
I am not saying that the earth is only 6,000 years old. No one knows--or can know--how old the earth is. That is beyond the realm of science.